Hole in Engine Block????

[mattsmall1972]

OK, somebody please tell me that the hole in this engine block is normal and if anything is supposed to go into it to block it up. This is a 1978 OMC 2.5L. I was in the process of cleaning this thing in prep for a quick paint job to prevent further rust and for the new exhaust manifold when I found this hole. I stuck a screwdriver in it and basically cleaned it out. It seems like a normal hole, not a rusted-through block. But I don't know why it's there, or if it's supposed to be there. It's not threaded in any way that I can tell. I stuck the end of a plastic survey flag through it (seen in picture) and I get a wet greasy gunk out of it, and it goes way, way in there. So, I really need some encouragement on this...<br /><br />

 

[Don S]

Re: Hole in Engine Block????

It's the block drain (Cooling water). It is supposed to be threaded. Obviously, it's been stripped out.<br />Might try retapping the hole a bit deeper if you have hole depth for the tap. Should be 1/4"NPT thread.

 

[mattsmall1972]

Re: Hole in Engine Block????

OK, I knew you'd come through on this... you're the man. I'll find the right thing for this. Whew, I thought I might have to buy a new engine. Thanks.

 

[mattsmall1972]

Re: Hole in Engine Block????

Don - please pardon my doubt, are you sure that this is block drain? The hole does not appear to have ever been threaded nor will a 1/4"NPT thread come close to fitting into that hole. The hole that is just to the left and below the red circle (the white pole just misses it) is definitely a 1/4"NPT thread, and it's much bigger. So it does not make sense to me that this one hole is so much smaller, even it the original drain plug was still in it. By chance to do you have references to it on the web anywhere?<br /><br />Thank you

 

[Don S]

Re: Hole in Engine Block????

I can't tell you what size it is from here, you will have to determine what will fit in it, but it IS the block drain hole for the cooling system. It's right at the bottom of the water jacket around the cylinders.

 

[tommays]

Re: Hole in Engine Block????

<br /><br />Are you talking about that hole ?<br /><br />tommays

 

[mattsmall1972]

Re: Hole in Engine Block????

Yes, that's hole that is definitely a block drain... I think. I pulled a drain plug from it earlier... I think. I might be all confused. Please help.

 

[Don S]

Re: Hole in Engine Block????

 

[mattsmall1972]

Re: Hole in Engine Block????

Wow! I really appreciate the time you give to me and this forum.